Home

azgcorr User Manual

1. typically 0 9996 nor eor grid coords at origin and cm No defaults are provided option TMS forces use of southern hemisphere for TM option mLAM h s1 s2 lao Ino eor nor la1 la2 Lambert Conical Lambert Conical Orthomorphic with one or two parallels s1 s2 lao Ino eor nor as TM above h hemisphere N north S south la1 la2 two standard parallels lats if la1 la2 single parallel projection used option OM Oblique Mercator option OM do s1 s2 sc xor yor lac la1 In1 la2 In2 if do 1 OM do s1 s2 sc xor yor lac Inc azc if do 1 do defining option 0 for centre and 2 points on centre line 1 for centre and azimuth of centre line s1 spheroid code or semi major axis s2 semiminor axis b reciprocal flattening f or eccentricity e 2 sc scale factor at centre of projection xor yor grid coordinates at origin lac Inc lat long at centre la1 In1 first point on centre line la2 In2 second point on centre line azc azimuth of centre line east of north Remote Sensing Scanner Processing System c Azimuth Systems 1996 2003 Version 3 00 16 20030131 Azimuth Systems User Guide AZGCORR option RSO Rectified Skew Mercator parameters as for Oblique Mercator above option NZ New Zealand projection New Zealand projection on International spheroid Hayford 1910 no parameters option DUTCH Netherlands National Grid Rijksdriehoeksmeting RD projection on Bessel 1841 spheroid no p
2. 1 ATrgyro 132 1 Roll gyro correction applied in scanner flag 0 no 1 yes Note 1 AThddat C8 16 HDDT tape external label name Note 1 ATcct C8 64 CCT tape external label name Note 1 ATtype C8 8 Daedalus ATM type eg 1268 ATid C8 32 ATM ID Remote Sensing Scanner Processing System c Azimuth Systems 1996 2003 Version 3 00 34 20030131 Azimuth Systems User Guide AZGCORR ATfov F32 1 Field of view dec degs ATpixfov F32 1 Pixel field of view ATpixrec 132 1 Pixels per scan recorded ATpixred 132 1 Pixels per scan reduction method 0 none 1 average 2 nearest ATpixsav 132 1 Pixels per scan saved ATsscan 132 1 Target start scan ATescan 132 1 Target end scan ATchan 132 1 Channels bands recorded ATbpix 132 1 Bits per pixels recorded ATgains F32 var Channel gains ATwavu F32 var Channel upper wavelength limit ATwavl F32 var Channel lower wavelength limit ATscps F32 1 Nominal scans per second recorded ATbbtf 132 1 Black body temperature saved type flag 0 fixed for file 1 table ATbb1 F32 var Black body 1 temperature ATbb2 F32 var Black body 2 temperature ATbbscan 132 var scan at which temp applies for table option ATcalfile C8 32 calibration file name ATcaltab F32 100 calibration values table ATradsc F32 var Channel radiance scaling multiplier ATrunits C8 32 Radiance units ATimgmin F32 var Channels minimum values excluding zero ATimgmax F32 var Channels maximum values excluding overflows ATimgzer 132 var
3. 6 GeoTIFF output A GeoTIFF output file can be created as for TIF but can only be from a level 3 file as the GeoTIFF file requires geolocation data for a rectangular image GeoTIFF files can be input into most of the main remote sensing image handle packages eg ERDAS ERMAPPER etc ERDAS from ver 8 5 will accept and allow viewing of more than 3 bands in the file GeoTIFF ver 1 1 4 in azexhdf 2 0 0 has some restrictions in defining map projections which affect some local European projections For the UK currently only the basic pre 1995 method for UK National Grid is supported When images are transferred to ERDAS and used with other images or vector data this should be remembered 7 4 7 Limitations and error messages azexhdf may not work correctly and may well crash if the input haf file was created by a previous program run that terminated with an hdf error This is one of many deficiencies in the HDF system which is unable to detect corrupted or improperly closed files azexhdf will correctly report if an input file is missing or not an HDF file It will then terminate Remote Sensing Scanner Processing System c Azimuth Systems 1996 2003 Version 3 00 26 20030131 Azimuth Systems User Guide AZGCORR A Commonly used Datum Shift and Spheroid values Datum shift d and map projection m options both may require numeric values for spheroids and datum shifts commonly used values are supplied below These are su
4. 64 recording media ATtype C8 8 Daedalus ATM type eg 1268 ATid C8 32 ATM ID ATfov F32 Field of view dec degs 1 ATfovp F64 3 details of reduced filed of view see below ATpixfov F32 1 Pixel field of view ATpixrec 132 1 Pixels per scan recorded ATpixred 132 1 Pixels per scan reduction method 0 none 1 average 2 nearest ATpixsav 132 1 Pixels per scan saved ATsscan 132 1 Target start scan ATescan 132 1 Target end scan ATchan 132 1 Channels bands recorded ATbands 132 var Channels bands saved to HDF file see note 3 below ATbpix 132 1 Bits per pixels recorded ATwavu F32 var Channel upper wavelength limit ATwavl F32 var Channel lower wavelength limit ATscps F32 1 Nominal scans per second recorded ATbbtf 132 1 Black body temperature saved type flag 0 fixed for file 1 table ATbb1 F32 var Black body 1 temperature ATbb2 F32 var Black body 2 temperature ATbbscan 132 var scan at which temp applies for table option ATsbb1 F32 var Black body 1 set temperature ATsbb2 F32 var Black body 2 set temperature ATvbb1 F32 var Black body 1 viewed DN average ATvbb2 F32 var Black body 2 viewed DN average ATsync F32 var 2 ATcal C8 16 indicates if data is calibrated ATcalver C8 16 version of calibration file ATcalfmt C8 16 format layout of calibration file ATcalfile C8 32 calibration file name ATcaltab F32 var calibration values table ATgains F32 var gains ATradsc F32 var Channel radiance scaling multiplier ATrunits C8
5. 7 2 basic use 7 3 options and parameters 7 4 applications of azexhdf A Commonly used Datum Shift and Spheroid values B Map projections and required parameters C BIL file and BIL STATS file details D AZSPS Level 1 and Level 3 HDF file details Remote Sensing Scanner Processing System c Azimuth Systems 1996 2003 Version 3 00 2 20030131 Azimuth Systems User Guide AZGCORR 1 Introduction to Azimuth Systems airborne remote sensing geocorrection program AZGCORR This program has been developed and refined over a period of years and is the result of the author s experience with airborne remote sensing since the 1980s The basic method used in azgcorr was first tested on images from an ATM scanner in 1989 using hand adjusted navigation Airborne Remote Sensing has become more common in recent years even with the competition from high resolution satellites The airbone sensor will of course always have its place as a geophysical instrument because for reasons of resolution spectral coverage fly at any time etc The contemporary emphasis for geographic data is on computer based location services typically using GPS positioning so the ability to position an aircraft acquired image on a standard map is now of great importance Nevertheless it is important to distinguish between the requirements for scientific use and consummer cosmetic uses An aircraft or satellite image can always be squashed to match a diagramatic map for ill
6. Channels no of zero values ATimgovr 132 var Channels no of overflowed values SCimtype 132 1 Image type flag 0 as source 1 resampled SCorder 132 1 Pixel order flag 0 I to r 1 r to I in direction of lines increasing SClndir 132 1 Scan line direction flag 0 flight direction 1 north up SCtiles 132 1 Tiles in image 0 not tiled single image gt 0 number of tiles SCbands 132 1 Bands in image SCpixels 132 1 Pixels in image SClines 132 1 Lines in image SCpixfmt 132 1 Pixel format flag O 8bit unsigned 1 16bit unsigned SCHDFfmt 132 1 Pixel HDF number format flag see HDF documentation for details SCimover F32 1 flag value indicating overflowed values see general note 2 SCimunder F32 1 flag value indicating underflowed or missing values see gen note 2 SCpixbytes 132 1 Bytes per pixel SCposn 132 1 Position data relation flag 0 posns per scan 1 posns per image SCaxes 132 1 Coordinate axes for position flag 0 along flt dir 1 N up SCxypix 132 1 relatio of coordinates to pixel flag O centre 1 BL SCpixwid F32 1 Pixel width x or scan direction metres SCpixhgt F32 1 Pixel height y or flight direction metres SCviewty 132 1 Image view type flag see general note 4 SCvplane 132 1 Image view y plane position metres SCposimag F64 var Image position coordinates for SCposn 1 see general note 5 SCposscan 132 1 Position info per scan content flag SCsused 132 var scans used in level 3 image field scan numbers SCbus
7. DEMs best fit required This will require that the LIDAR DEM grid is accurately processed to fit the local map at the desired scale So for a UK example once this is done then ex7 will apply 5 9 controlling output image interpolation Options are provided to do the two passes of the interpolation using one of three methods a cubic spline b linear and c nearest neighbour By default cubic spline is used resulting in a smooth image surface but will generate pixel values intermediate to adjacent ones which may have DN values not in the original image For uses such as classification nearest neighbour may be more appropriate as no new values are created Remote Sensing Scanner Processing System c Azimuth Systems 1996 2003 Version 3 00 12 20030131 Azimuth Systems User Guide AZGCORR Users are encouraged to try different methods to see how which best fits their application It worth noting that linear and nearest neighbour are much faster than cubic If aircraft motion was extreme for any reason it is possible for the edge of particularly ATM images with their large field of view to open up This will be seen as black inlets encroaching into the image Parameter g gm gr canbe used to control this gm is the size in pixels of a the minimum gap ie if a gap of greater than this occurs it will not be interpolated across gr is the count of pixels considered as a run of good pixels 5 10 BIL input of image data Imag
8. Scanner Processing System c Azimuth Systems 1996 2003 Version 3 00 17 20030131 Azimuth Systems User Guide AZGCORR option hsu Geod spheroid height correction height correction for WGS84 geoid spheroid applied as a constant based on map centre option I sten Input scan lines to process option Is sts ens Scan line numbers to limit processing st and en are scan counts in the image from 0 and sts ens are original instrument allocated scan numbers in the range of items CAsscan CAescan CASI vgroup or ATsscan ATescan ATM vgroup Default with I or Ils missing is to process all scans on the input file b Input bands to process option bl b1 b2 1 List of input bands to process option br b1 bn Inclusive band range to process Note that if less than the total bands are processed output bands may be reordered For example with b 532 1 the output image bands will be 1 input band 5 2 input band 3 etc Default with no b option is to process all input bands Cis CASI processing options option call process all present data in default modes option cspa DO NOT process IMG if spatial def process option cils process ILS def do not process option csrc process SRC def do not process option cspe process spectral def do not process option cspi process spectral as complete image option cspw process enhanced spectral at minimum width default ie not equal in size to SRC image Default for ILS
9. and spectral is to save pixel coords as extra bands and apply no image interpolation option cc o p fv CASI ccd and lens details CASI ccd lens details to replace program defaults o optic axis nadir pixel n or n 5 ie 230 or 225 5 but not 124 3 p port pixel 0 pixel 1is on the port side 1 max pixel is on the port side fv lens field of view in decimal degrees option ccd o p fv pfv tp general ccd details to replace file defaults o optic axis nadir pixel decimal p port pixel 0 pixel 1 1 max pixel fv lens field of view in degrees piv field of view port pixel to optic axis tp total pixels in field of view option cca pt load casi ccd pixel view angle table from external file pt file path name for pixel view angle table Angles are from port to starboard in flight direction in decimal degs and must equal in number the current viewed full ccd pixels for all processing Remote Sensing Scanner Processing System c Azimuth Systems 1996 2003 Version 3 00 18 20030131 Azimuth Systems User Guide AZGCORR i Output image interpolation control option ic sm Bi cubic Method uses a cubic tensioned spline sm is the spline tension This is the default if i is not used sm smoothing value 0 001 50 0 def 1 0 0 001 is very smooth 50 is linear interp option il linear option in Nearest neighbour option il2 second pass interp is linear option in2 second pass interp is nearest n
10. hsu es gsepfile then as ex2 ex6 The first example assumes UK based data so the internal table can be used the second supplies a file which may cover any of the globe 5 6 using DEMs all consistent coordinates As descussed in detail in section 3 4 above DEM grids have to be consistent with the datum shift and map projection selected This will be the case for DEMS obtained form local maps or mapping agencies azgcorr mUK99 osgb99 eh sitegrid then as ex2 ex7 The DEM on file sitegrid is already UK99 and contains a file header describing the contents The issue to watch is that the grid completely surrounds the image data if it does not the missing parts will be extrapolated level and parts of the image will not fit a map accurately Watch for the DEM limits message from the program 5 7 using LIDAR DEMs no map fit required If the DEM is generated but not controlled to the local datum eg from scanned photos or LIDAR care has to be taken to avoid what can be large mismatches If the scanner aircraft and the LIDAR aircraft are both gps positioned two choices are possible a if the resultant corrected image does not need to match well an existing map then the LIDAR data must be kept in WGS84 coordinates and use azgcorr dNO mTMw 3 eh lidardem as ex2 ex8 No datum shift if enforced and a tranverse mercator projection is used with default parameters EXCEPT the spheroid is WGS84 and the central meridan is 3 west 3 5 8 using LIDAR
11. of view option v verbose listing request Remote Sensing Scanner Processing System c Azimuth Systems 1996 2003 Version 3 00 20 20030131 Azimuth Systems User Guide AZGCORR 7 azexhdf data export utility 7 1 introduction azexhdf allows the user to extract list or reformat selected data from an AZSPS HDF file Output files may be in one of several standard layouts and formats for transfer to image analysis and display programs Spported output formats are BIL BSEQ Sun raster TIFF GeoTIFF as well as ascii space separated multiplexed vector flat files Selection of data may be by HDF file item name spectral bands pixel or line limits 7 2 basic use Use At unix prompt type azexhdf options h hdf_file_path Usage information obtained by executing program with no command line parameters 7 3 options and parameters option h fp hdf file path fp file path for hdf file to access option hg vg vgroup to list vg Vgroup name for single vgroup access hg not present all vgroups listed default option hd vd vdata to list vd single vdata to list file option B fp convert image data to BIL binary file fp file path for created file option BS fp convert image data to BSEQ binary file fp file path for created file option Bv verbose detail listing for conversion switches on verbose listing mode for BIL or BSEQ file creation option Bs requests output header stats file creates a heade
12. option vf fp filepath for complete vector output option v max max items to list for vectors in summary listing def 1 NB this is for listings only option vn item HDF VData vector data item name item VData name repeat use for several items NB max of 12 items NB this is for VData items only NOT SDS image items option vi st en vector index limits to save file sten start and end index 0 gt to save from HDF VData items to file option vq fmt format for qual vectors items fmt C format description for navigation qual item listings default is 08Ix option vs add scan number in col 0 of multiplexed output This is to be used with NVscnum and NVscsecs only option vp nO n1 1 user supplied list of decimal places nO no of decimal places in order of vector vn items This is to control ouput listing of a set of multiplexed vectors if only nO is given this will apply to all items defaults dps are v lt 90 5 else 5 except lat and lng are 7 dps option vm ALL requested vectors to be output multiplexed NB vectors must be from the same Vgroup and of equal length eg pitch roll and heading Remote Sensing Scanner Processing System c Azimuth Systems 1996 2003 Version 3 00 23 20030131 Azimuth Systems User Guide AZGCORR Notes 1 Filenames can be complete paths 2 Vgroup and data item names are case sensitive 3 Band numbers are 1 relative 4 Pixel and line patch limits are zero relative 5 for
13. post processed navigation linked to scanner data by gps time and scan number Sco scan coords final per scan coordinates corrected to scan nadir and transformed to the scanner MAP mapping datum and map projection details used to create a level 3 image LV2 level 2 level 2 details ATM ATM ATM data from original Daedalus system ATM2 ATM2 ATM data from AZ16 system CAS CASI CASI or other ccd scanner data Navigation vector items are stored compressed using a simple multiplier which is also stored in the HDF file This saves disc space without loss of precision Image items are stored as unsigned integers again scaled to best preserve precision Optionally image items may be stored as floating point but file sizes will be doubled Using unix utilities HDF files may be copied moved or archived but NOT viewed edited concatentated or truncated Data items are described by name data type maximum number of occurences of the type and a brief descripton Notes specific to a Vgroup appear after the items decsription for that VGroup and general notes appear at the end of the document VGroup PROCESSING Contains details of the file processing level creation and authorship Vgroup is created by SITEINIT with PRlevel updated by appropriate programs Vgroup name PRO Vgroup title Processing Data item prefix PR Item name type maxv description PRdesc C8 64 Vgroup description Latest processing level of file PRlevel C8 8 Latest processing leve
14. required In the case of completely offshore sites where geoid spheroid correction is required provide any grid file the program will create a zero filled grid and apply the correction ignore the no data message 3 5 Time Time only becomes important when the Level 2 options to calculate pixel view and solar illumination angles are used Except for these solar calculations for which UTC is required GPS time of day is used throughout for identifying and merging data Full details of time will be available with the integrated release of level 2 processing in azgcorr 3 6 Image Interpolation In the current release three image interpolation options are provided a bi cubic b bi linear and c nearest neighbour The first two methods will produce pixel values not in the input image method c will not generate extra values and must be used for classified images In all cases image data is only used if it has DN values between the upper and lower limits stored in SCimover and SCimunder respectively User control is also provided for defining the size of gaps that will be interpolated or filled nearest neighbour and the minimum number of pixels considered to be a good run Both these parameters have limited importance as they only affect the edge of images where the pixel distortion makes the data of little value and generally can be left to default Care must be taken when a small pixel size is used together with large aircraft motion
15. version 2 0 0 onwards local libraries for TIFF and GeoTIFF are not required Remote Sensing Scanner Processing System c Azimuth Systems 1996 2003 Version 3 00 24 20030131 Azimuth Systems User Guide AZGCORR 7 4 applications of azexhdf 7 4 1 HDF file contents listing typing azexhdf h hdf_file_path at the unix prompt h is optional Will obtain a summary listing to stdout Parameters hg and hd with appropriate VGroup and data item names can be used to retrict the listing to one VGroup or just 1 data item By default vector items listings are limited to 5 items at the start of the vector and the last one if there are more than 5 values To list more of the values use option v to get the required number from the start of the vector or vi to get a selected part from the middle eg azexhdf t1 hdf Will give a summary listing of all items on t1 hdf eg azexhdf hg NV hd NVlat v 100 t1 hdf Will get a listing of the first 100 and last values of the NAV VGroup vector containing aircraft latitudes For image items stored as SDS listing are obtained by using the options bl to select one or more bands and p to define a pixel patch By default the item listed will be ATdata for ATM VGroup and CAimage for CASI VGroup other items can be selected using option d 7 4 2 Mulitplexed vectors Selected vectors can be listed or output to an ascii file multiplexed This is only valid if the items are related and exactly match in leng
16. 0131 Azimuth Systems User Guide AZGCORR The level 3 file from the same data set is scanner AZ16 item ATdata proclevel 3 bfile a3 bil pixels 2190 bands 1 lines 393 pixfmt 0 radscale 1 00 pixby 2 bandby 4380 band 1 obnd 1 min 24662 max 32310 xys 259176 0 291036 0 3 000 0 000 0 000 3 000 histcols 256 hbnd 1 hzer 148652 hovf 0 hcol peuka followed by 1 band histogram Remote Sensing Scanner Processing System c Azimuth Systems 1996 2003 Version 3 00 30 20030131 Azimuth Systems User Guide AZGCORR D AZSPS Level 1 and Level 3 HDF file details The HDF layout used for the Azimuth Systems scanner processing system AZSPS is described below A restricted subset of HDF interfaces has been used All data items are only identified and accessed by name A two level item hierachy is used VDatas in single level VGroups Data items are only stored as single dimension VDatas with one or more values or three dimensional scientific data sets SDS linked to particular VGroups Data items can be read using general released HDF utilities or the supplied utility azexhdf HDF used in this release is HDF4 1r4 Some items are application related and the user is refered where relevent to the appropriate processing program VGroups and contents Nmeonic name contents PRO processing details of the system used to create the file MIS mission descriptive details of the flight site and site time and scan limits NAV navigation all related but
17. 1 fn level 1 HDF file path fn input Level 1 HDF file path requirement MANDATORY default NONE option 3 fn level 3 HDF file path fn output Level 3 HDF file requirement MANDATORY default NONE option p dx dy Output pixel size Output pixel x y sizes in metres Requirement MANDATORY default NONE option B btsof BIL or BSEQ file content details b total bands on file t number type on file O uint16 1 float32 S scale o Offset to convert B file values for geom correction and saving as uinti6 v p s o f fill value for bad pixels good pixels are lt f if f O the default values of 0 and Oxffff uint16 or 10e30 float32 are assumed requirement MUST be used if Bi or Bs are used defaults b NONE s 1 0 o 0 0 option Bi fn BIL file path fn BIL input file Default none option Bs fn BSEQ file path fn BSEQ input file Default none d Geodetic datum shift details For details of commonly used data shift values see Appendix A Remote Sensing Scanner Processing System c Azimuth Systems 1996 2003 Version 3 00 14 20030131 Azimuth Systems User Guide AZGCORR option dNO No datum shift performed No datum shift is performed data remains in WGS84 throughout processing option d95 OS 1995 datum shift method applied Ordnance Survey 95 method using GRS80 datum See Ordnance Survey publication National Grid ETRF89 Transfromation Parameters Geodetic Information Paper No 2 2 95 V1 2
18. 132 1 CASI field tape file number Mlaper 132 1 CASI used aperture Mliscanner C8 8 Scanner name ATM or CASI Mlslimit 132 1 Site limit type flag O none 1 time 2 scan 3 both Misday 132 1 Day number of site start time 1 366 Mistime 132 1 Time of site start HHMMSS Mletime 132 1 Time of site end HHMMSS Mlsscan 132 1 Scan number at site start Mlescan 132 1 Scan number of site end Mllimits C8 128 description of site limits VGroup NAVIGATION Contains observed navigation from aircraft survey instruments and base reference station Up to two sets of independent navigation sets can be saved with position and attitude with each set having independent timing All times in seconds are consistent and are used to link navigation observations and scans GPS data is inserted by azjps or azimport and scan sync by azjps azatm or azcaschk VGroup name NAV Vgroup title Navigation Data item prefix NV Item name type maxv description NVdesc C8 64 Vgroup description GPS navigation and scan synchronisation data NVprog1 C8 40 Vgroup 1st processing program NVprog2 C8 40 Vgroup 2nd processing program NVprog3 C8 40 Vgroup 3rd processing program NVsys1 C8 40 Prime aircraft survey navigation system NVsysii C8 40 Prime system infomation NVsys2 C8 40 Secondary aircraft survey navigation system NVsys2i C8 40 Secondary system infomation NVsys3 C8 40 Third aircraft survey navigation system NVsys3i C8 40 Third system infomation NVbase C8 40
19. 32 Radiance units ATimgmin F32 var Channels minimum values excluding zero ATimgmax F32 var Channels maximum values excluding overflows ATimgzer 132 var Channels no of zero values ATimgovr 132 var Channels no of overflowed values SCimtype C8 32 Image type source or resampled 0 fill SCorder C8 32 Pixel in scan order Left gt Right or Right gt Left direction of lines increasing SClndir C8 32 Scan line direction flight direction or north up SCtiles C8 32 Tiles in image not tiled single image or number of tiles SCbands 132 1 Bands in image SCpixels 132 1 Pixels in image SClines 132 1 Lines in image SCpixfmt C8 1 Pixel format 8bit unsigned 16bit unsigned SCHDFfmt 132 1 Pixel HDF number format flag see HDF documentation for details SCimover F32 1 flag value indicating overflowed values see general note 2 SCimunder F32 1 flag value indicating underflowed or missing values see gen note 2 SCpixbytes 132 1 Bytes per pixel SCposn C8 32 Position data relation posns per scan posns per image SCaxes C8 32 Coordinate axes for position along flt dir N up SCxypix C8 32 relatio of coordinates to pixel centre BL SCpixwid F32 1 Pixel width x or scan direction metres SCpixhgt F32 1 Pixel height y or flight direction metres SCviewty C8 32 Image view type see general note 4 SCvplane 132 1 Image view y plane position metres SCposimag F64 var Image position coordinates for SCposn 1 see general note 5 SCposscan 132 1 Positi
20. 32 var SRC band minimum excluding zeros CAsrcmax F32 var SRC band maximum excluding overflows CAsrczer 132 var SRC band zeros CAsrcovr 132 var SRC band overflows CAilsmin F32 var ILS bands minimum excluding zeros CAilsmax F32 var IILS bands maximum excluding overflows CAilszer 132 var ILS bands zeros CAilsovr 132 var ILS bands overflows SCimtype 132 1 Image type flag 0 as source 1 resampled SCorder 132 1 Pixel order flag 0 I to r 1 r to in direction of lines increasing SClndir 132 1 Scan line direction flag O flight direction 1 north up SCtiles 132 1 Tiles in image 0 not tiled single image gt 0 number of tiles SCbands 132 1 Bands in image SCpixels 132 1 Pixels in image SClines 132 1 Lines in image SCpixfmt 132 1 Pixel format flag 0 8bit unsigned 1 16bit unsigned SCHDFfmt 132 1 Pixel HDF number format flag see HDF documentation for details SCimover F32 1 flag value indicating overflowed values see general note 2 SCimunder F32 1 flag value indicating underflowed or missing values see gen note 2 SCpixbytes 132 1 Bytes per pixel SCposn 132 1 Position data relation flag 0 posns per scan 1 posns per image SCaxes 132 1 Coordinate axes for position flag 0 along flt dir 1 N up SCxypix 132 1 relation of coordinates to pixel flag O centre 1 BL SCpixwid F32 1 Pixel width x or scan direction metres SCpixhgt F32 1 Pixel height y or flight direction metres SCviewty 132 1 Image view type flag see ge
21. 94 Remote Sensing Scanner Processing System c Azimuth Systems 1996 2003 Version 3 00 27 20030131 Azimuth Systems User Guide AZGCORR B Map projections and required parameters Remote Sensing Scanner Processing System c Azimuth Systems 1996 2003 Version 3 00 28 20030131 Azimuth Systems User Guide AZGCORR C BIL file and BIL STATS file details The standard flat file format used for remote sensing data is Band Interleaved by Line BIL For historic reasons this has no header to describe the file contents nor data value format azgcorr can also generate similar files in Band Interleaved by Pixel BIP and Band Sequential BSEQ but these are used less often azexhdf can generate BIL files and an associated AZSPS file that contains in readable text a description of the BIL file contents This description file is follows no standard as there is none but may be used and adapted for user purposes There is also an option to output a per band histogram to this file See azexhdf running instructions for how to create the files BIL format means that for each scan line all pixels in sequential order acroos the scan appear in band order for the scan ie line O band0O pixel 0 pixel n band 1 pixel 0 pixel n band m pixel 0 pixel n line 1 baad 0 pixel 0 pixel n os BIL files output by azexhdf have no pack bytes at any place in a band or line If the AZSPS header information file is requested it consists of a set of n
22. Azimuth Systems User Guide AZGCORR AZIMUTH SYSTEMS UK Airborne Remote Sensing Geocorrection package AZGCORR User s manual Reflects azgcorr version 4 0 0 February 2003 Last revised February 2003 Copyright c Azimuth Systems UK 1996 2003 All rights reserved Remote Sensing Scanner Processing System c Azimuth Systems 1996 2003 Version 3 00 1 20030131 Azimuth Systems User Guide AZGCORR Contents 1 Introduction 2 Summary of functionality 3 Geo correction concepts in azgcorr 3 1 Goals for correction 3 2 Navigation relation to Datums and Spheroids 3 3 Map projections 3 4 Digital Elevation data 3 5 Time 3 6 Image Interpolation 3 7 CASI and other CCD scanner corrections 3 8 Viewing the results 4 Using azgcorr 4 1 Introduction 4 2 Internal data files used by azgcorr 4 3 External data files used by azgcorr 4 4 System requirements and Practical aspects of running the program 5 Applications of azgcorr 5 1 to obtain online program help 5 2 basic correction 5 3 changing the map projection no datum shift required 5 4 changing the datum shift and map projection 5 5 improving mapping accuracy without a DEM 5 6 using DEMs all consistent coordinates 5 7 using LIDAR DEMs no map fit required 5 8 using LIDAR DEMs best fit required 5 9 controlling output image interpolation 5 10 BIL input of image data 5 11 typical complete run 6 azgcorr run options and parameters 7 azexhdf data export utility 7 1 introduction
23. Base reference station navigation system NVbasei C8 40 Base information NVpos1i C8 40 position set 1 information NVatt1i C8 40 attitude set 1 information NVpos2i C8 40 position set 2 information NVatt2i C8 40 attitude set 2 information NVspher C8 40 Spheroid name for aircarft navigation system NVdatsh C8 40 Datum shift applied to aircraft navigation system NVtbase C8 40 basis of all timiing NVacor f64 1 vector of aircraft nav posn to scanner offset NVut2gt 64 1 time correction used to convert NMEA UTC times to GPS time in seconds NVjday 132 1 Year day for site start NVstime 132 1 Time of site start HHMMSS NVetime 132 1 Time of site end HHMMSS NVtime sl32 var Time of position set 1 observations GPS dec secs NVutc sl32 var Time of position set 1 obseravtions UTC dec secs NVlat 132 var Latitude dec degs NVIng 132 var Longitude dec degs NVhgt sl32 var Spheroid height metres NValt 132 var Recorded altitude above local datum metres NVqual UI32 var position quality flags NVasecs sl32 var Time of attitude set 1 observations dec secs NVroll sl32 var Aircraft roll positive right wing down dec degs NVpitch sl32 var Aircraft pitch positive nose up dec degs Remote Sensing Scanner Processing System c Azimuth Systems 1996 2003 Version 3 00 32 20030131 Azimuth Systems User Guide AZGCORR NVhead sl32 var Aircraft heading 0 360 clockwise from true north dec degs NVaqual UI32 var attitude quality flags NV
24. This is the default if no d option is used option dDUTCH for Netherlands National Grid No parameters option d7 sc a p2 dx dy dz rx ry rz sc 7 parameter Bursa Wolff shift Applies a 7 parameter Bursa Wolff single point transformation sc spheroid code 1 if a and p2 are supplied 0 Int Hayford 1950 1 Airy 1830 UKNG a semi major axis p2 semi minor axis or reciprocal flattening or eccentricity metres dx y Z origin shift in metres rx y z axis rotations in secs sc scale excess in ppm ie scale 1 sc 1000000 There are no numeric defaults except as mentioned m Map projection details For details of map projection and required parameters see Appendix B If m is not supplied the built in conversion method UK National Grid 1995 is used option mUKNG TM set to UK National Grid This uses the Airy 1936 spheroid and has no built in soheroid geoid correction and requires a seven parameter datum shift to be applied see d7 above and datum shift values in Appendix A option mUK99 fp TM set to UK Nation Grid 1999 method fp file path to OSGB99 correction file The details of this method using OS supplied correction grids OSTN97 and OSGM91 are described in OS publication User Guide v1 2 12 1999 option mUK02 fp TM set to UK National Grid 2002 method fp file path to OSGBO2 correction file This method is similar to the 1999 one but uses an iteritive reverse conversion and a correction grid described are being more
25. a UINT16 image items have two special values Oxffff 65536 indicates an overflowed value zero indicates underflowed or missing data b FLOAT32 image items have two similar special values to allow for flexibility for level 2 processing these values are stored in ATM and CAS Vgroup items SCimover and SCimunder The following rule must be adhered to to avoid image data loss valid image items must be between SCimover and SCimunder images values gt SCimover and lt SCimunder will be omitted from level 3 calculations Note that these items are valid for UINT16 and FLOAT32 image data Default values are UINT16 SCimover 65536 0 SCimunder 0 0 Default values are FLOAT32 SCimover 1 0e 30 SCimunder 1 0e 30 3 Tiled images Image tiling is indicated by SCtiles gt 0 Image is tiled into side by side squares by no of pixels Image data for tiles are stored in the image data items ATdata CAimage spatial mode CAsrc Note that CAimage spectral mode and CAils are not tiled and always stored in one piece The key to the position of tiles is stored in the appropriate VG xy item after scaling Image data for squares may be in any order from the total image area the key may be ordered for best access or other reasons a SCpxyn SCpxy_sc ATimgxy CAimgxy CAsrcxy and CAilsxy are only used if the image is tiled b In none tiled files image items are stored as bands lines and pixels Typically Level 1 and 2 data is none tiled and Level 3 ma
26. accurate The grids released by the OS have been cut to about 10Km offshore around coasts The grid supplied for use in azgcorr has been filled in these offshore areas by adjusted values from the 1999 method grid option mIRNG TM set to Irish National Grid As of azgcorr version 4 0 0 the latest 02 2003 accurate conversion method for Ireland has not been included contact Azimuth Systems for further information Remote Sensing Scanner Processing System c Azimuth Systems 1996 2003 Version 3 00 15 20030131 Azimuth Systems User Guide AZGCORR option mUTM cm UTM with central meridian TM set to UTM with supplied central meridan longitude cm signed decimal degrees option mUTMZ zo UTM to zone zo 1 60 Zones are 6 degrees wide and numbered 1 to 60 1 is 180 west to 174 west with central meridan at 177 west UK is in zones 30 3 west and 31 3 east option mTMw cm TM using WGS84 spheroid This option is provided to allow a quick look at non UK data without having to fill in all the parameters to keep the map projection in WGS84 spheroid option mTM s1 s2 lao Ino sc nor eor Comprehensive TM Transverse Mercator with user supplied parameters s1 spheroid code or semi major axis a 0 INT 1 Airy 3 WGS84 s2 semi minor b or reciprocal flattening f or eccentricity e 2 set this to 0 if s1 is a spheroid code lao projection origin latitude Ino central meridian longitude cm sc scale factor at cm
27. ame and value pairs separated by spaces describing the contents and layout of the BIL file these are scanner AZ16 CASI etc item name of image item from HDF file Atdata CAimage etc proclevel 1 2 or 3 bfile the BIL file being decribed pixels p bands b lines p b and are integer total for each dimension output pixfmt 0 UINt16 and 1 4 byte float radscale 1 00 means unscaled pixby bytes per pixel bandby total bytes for a complete band band b obnd ob min m max x repeated for each band in its output order b is from 1 to bands output ob is the original band number min and max are the band DN limits excluding 0 and overflow values xys for a level 3 file this is the SCposimag vector items 2 to 7 see HDF description general note 5 If a histogram was requested the following is present histcols n n is the number of columns in each histogram then the following are repeated for each band output hbnd b hzer z hovf o hcol b is band output z is 0 column entry and o the overflow entries then histogram columns 10 per line A typical level 1 file would be scanner AZ16 item ATdata proclevel 1 bfile a1 bil pixels 718 bands 1 lines 5167 pixfmt 0 radscale 1 00 pixby 2 bandby 1436 band 1 obnd 1 min 24531 max 24887 histcols 256 hbnd 1 hzer 0 hovf 0 hcol 0000000000 etc for rest of 1 band histogram Remote Sensing Scanner Processing System c Azimuth Systems 1996 2003 Version 3 00 29 2003
28. any input scan lines d too small a roll partition on Sun or Linux The main points to note when running azgcorr is its potentially long run time Users are advised until they obtain a feel for these times to restrict the number of bands selected for correction and to use an output pixel size no smaller than 5 metres Run times are several times longer if a DEM is present typical times for ATM are 20 minutes per 1000 scans per band on a Sparc 5 The program allocates dynamically many large buffers depending on the direction of the data and the output pixel size Memory is inversely related to the pixel size The program will halt with an error message if too little memory is available The program gives the total size of buffers allocated in the summary listing It is important to note on a Sparc workstation that the amount of useable memory assuming a user has no installation restrictions is about twice the actual RAM provided the disc swap partition is large enough for all tasks trying to run concurrently Remote Sensing Scanner Processing System c Azimuth Systems 1996 2003 Version 3 00 10 20030131 Azimuth Systems User Guide AZGCORR 5 Applications of azgcorr This section describes how to achieve desired results using the various control parameters Throughout the section for clarity on local file paths will be given the user may use full paths for any file in their place There are no defined filnaming requirements bu
29. ar coordinate set using a map projection Representing points on a spheroid by points on a flat surface is at best a compromise For survey use only a few map projections have the required characteristics of accuracy and scale and direction representation these are a Transverse Mercator eg UTM UK National Grid etc b Lambert Conical Orthomorphic c Universal Polar Stereographic above 80 degs north or south d other local specially designed ones eg Dutch New Zealand Other projections included are Mercator Oblique Mercator and Rectified Skew Mercator Each of these projections has a set of defining parameters usually agreed on a national scale azgcorr allows the selection of these projections and parameters details are described below Remote Sensing Scanner Processing System c Azimuth Systems 1996 2003 Version 3 00 6 20030131 Azimuth Systems User Guide AZGCORR 3 4 Digital Elevation data From the above discussions on datums and map projections it should be clear that elevation data is a measure of heights above some datum on a given spheroid and without transformation or other massaging can only be used in the context of this spheroid If the data is also positioned in map projection grid coordinates it is even more closely linked Consequently care must be taken that selected datum shifts map projection and DEM data are all self consistent Elevation data may be input to the program as azgcorr internal for
30. arameters a Corrected image alignment relative to map option an North up Default if a is not used option af Rectangle centred on flight line option aaz az user clockwise angle from grid N option pab Output pixel coordinate alignment If this option is present pixel coordinate limits are aligned at bottom left SW corner If this option is not present coordinate limits are aligned at the centre of pixels NB1 aligning at bottom left implies final image limits are to the outside edge of the peripheral pixels NB2 CASI spectral enhanced spectral and ILS coords are always returned pixel centred option r rv Coordinate rounding rv coordinate rounding value def is pixel size rounding is to multiples of rv option ro xm ym XX yx Enforced output limits Output image enforced x y limits grid coords allows different data sets to be matched NB wrong values may extend the image and cause runtime memory problems and large file size h Aircraft height control option h ht Constant height ht aircraft height above ground option hn Navigation height used Selects the use of GPS navigation height This is the default if no h is used option hs sc Navigation height with correction Same as hn but allows a user constant height correction to be made sc height correction to be added to aircraft hgt Requirement options hn or hs MUST be used with DEM and geoid spheroid correction Remote Sensing
31. e data may be extracted from a level 1b HDF file accessed by a user program to create an equivalent size and layout BIL file which is then input to azgcorr in place of the Level 1b data for geocorrection a run sequence to do this would be azexhdf bl 235 1 h a1 hdf Bs B atraw bil userprogram Bs a1raw bil stats Bin a1raw bil Bout a1new bil azgcorr 1 a1 hdf B 1 1 1 0 0 0 0 Bi a1new bil 3 a3 hdf The first azexhdf exports 3 bands in BIL layout to file a1raw bil by selecting Bs a second file is created airaw bil stats which maybe input to a user program to obtain the details of the BIL file without having to manually tranfer them see Appendix userprogram optionally uses the stats file and input image data from a1raw bil performs some calculation which for this example only creates 1 band and outputs the result image to ainew bil It does matter if this file is described as BIL or BSEQ as it only has one band both will be identical The azgcorr run still requires the original level 1b HDF file a1 hdf as well as the user created BIL file ainew bil and the parameters describing this file These indicate there is 1 band data in floating point no rescaling required and standard blank area infill required Corrected output will be to a3 hdf Note that a current restriction is the number of lines and pixels must the same throughout so the user program must not change the number of lines or pixels 5 11 typical complete run Batch scrip
32. e filename or a header may be used to avoid using this ed option in this case use eh to give the file name or data order 0 rows x S gt N 1 rows N gt S c cols r rows xm ym SW corner coords XX YX NE corner coords gi grid increment grid values on file must be separated by space s and may have decimal points NB only ONE file may be present option eh fn flat file with header fn DEM file path for flat file with a header header is the ed items separated by spaces eg 0512 102400511 1023 1 0 option es fn fn geoid spheroid separation grid file path if fn NO no geoid spheroid correction will be applied Default if es is not present is to use program built in g s values which cover UK SW 49 75 N 7 5 W to NE 60 75N 2 75 E Sites outside this range must use a g s file option n Navigation control option nacprh sign control of attitude items p r h 0 for use item without sign alteration 1 for use with signs reversed 2 for don t use ie set attitude item to zero nav may them be used to give a constant value NB normal sign convention assumes pitch is ve nose up roll is ve port wing up head is ve clcokwise from nose option naprh attitude corrections to be added p r h values in signed degrees to be added to the attitude value after applying option in nac option ns reverse scan direction scan direction is assumed to have pixel 0 from the input file on the starboard side of the field
33. ed 132 var bands used in level 3 image level 1 band numbers SCpxyn 132 1 No of pixels per side of tile SCpxy_sc F64 1 Image xy scale multiplier ATimgxy 132 var Image tiles coordinate list ATdata SDS 3xvar Image data ATM notes 1 Items sbend rgyro hddt and cct are specific to the original ATM system VGroup ATM2 Version for AZ16 recorded data note that some parameters have been changed from numerical flags to decriptive text to mak ethe Vgroup more readable Contains ATM scanner recording parameters and recorded calibrated or geometrically corrected image data stored as 16 bit integer to level 1b and either 16 bit integer or 32 bit floating for level 2 and level 3 Level 1 data is inserted by ATM_1 Data recorded with the DEI320 has 12 channels and from the AZ16 11 channels Vgroup name ATM2 Vgroup title ATM2 Data item prefix AT Item name type maxv description ATdesc C8 64 Vgroup description ATM scanner details calibration and data Remote Sensing Scanner Processing System c Azimuth Systems 1996 2003 Version 3 00 35 20030131 Azimuth Systems User Guide AZGCORR ATprog1 C8 40 Vgroup 1st processing program ATprog2 C8 40 Vgroup 2nd processing program ATprog3 C8 40 Vgroup 3rd processing program ATprog4 C8 40 Vgroup 4th processing program ATsbend 132 1 Sbend correction applied in scanner flag O no 1 yes Note 1 ATrgyro 132 1 Roll gyro correction applied in scanner flag 0 no 1 yes Note 1 ATrmedia C8
34. eighbour option ic2 sm second pass interp is cubic sm smoothing option itg thinning option on second pass interpolation g multiples of pixel spacing default 0 5 Pixels are omitted if closer together than g option g gm gr Image gap control gm gap size in multiples of pixel size ie gap metres gm pix_size gr good data run which will be interpolated These controls only affect the edge of the image as gaps rarely occur elsewhere In general the defaults should be used Defaults gm 4 gr 4 e Digital Elevation Model DEM control option e fn Digital Elevation file fn DEM file path may be repeated 8 times file s may be NTF contour OR grid OR internal grid format but not mixed option eg gr DEM grid increment For use with NTF contour files defines the saved DEM grid increment should be gt 2 pix inc Default 10 metres option ef DEM force slow search for ground intersection This option is occasionally needed in areas of rapid topographic change steep slopes option ez v DEM fill grid edge v value to fill empty grid edge nodes Default fill with nearby values Remote Sensing Scanner Processing System c Azimuth Systems 1996 2003 Version 3 00 19 20030131 Azimuth Systems User Guide AZGCORR option ed or c r xm ym xx yx gi flat file ascii DEM definition This defines the contents of a flat file containing DEM values Files may have no header in which case e fn gives th
35. ernal files from HDF4 to HDF5 or EOS HDF5 d provide access to pixel view vectors for file output or use in level 2 algorithms e allow integrated user generation of level 2 products f provide multiple swath support to combine several flight lines g provide an interpolation proceedure to correct all bands on a file in one pass If users wish to make suggestions or have input into future developments they should contact Bill Mockridge at Azimuth Systems UK billm globalnet co uk 1 2 Trademarks OSTN97 OSGM91 OSTNO2 OSGM02 OSGB36 are trademarks or registered trade marks of UK Ordnance Survey original correction data supplied under these items are c Crown Copyright Other Products and company names may be trademarks of their respective owners Remote Sensing Scanner Processing System c Azimuth Systems 1996 2003 Version 3 00 3 20030131 Azimuth Systems User Guide AZGCORR 2 Summary of azgcorr functionality azgcorr combines multi spectral scanner image data and post processed navigation and produces a map projection referenced rectilinear output image corrected for aircraft position attitude and ground surface separation computed from aircraft spheroid height digital elevation data and geoid spheroid separation estimates Special processing is available for non image data eg CASI spectral and ILS corrected pixel coordinates are saved to allow positioning of pixels either on a map or scene image Navigation and ima
36. es 2 Image items On all AZSPS file levels image items are stored as HDF SDS Scientific Data Sets The layout and dimensions have been chosen so that the line dimension is variable Data is stored in the SDS items with the following convention Level 1 pixel order is as recorded by the instrument eg for the ATM pixel 0 is on the port side of the flight path Line order is as recorded in flight direction Band order is from 1 to however many bands Level 3 If the image is created as a north up one then it is ordered for quadrant 1 ie pixels increase as x increases left to right lines increase as y increases from south to north of image If the head up image creation was selected then the images axes are x across the flight direction increasing left to right with pixel 0 on the left y is in flight direction increasing bottom to top of image line 0 is at the bottom Remote Sensing Scanner Processing System c Azimuth Systems 1996 2003 Version 3 00 38 20030131 Azimuth Systems User Guide AZGCORR Level 3 images outside the flight line area are zero filled Note that azexhdf has options to create output files ordered to suit other conventions Image items are either direct instrument recorded data or values derived from these Allowance is made for values overflowed underflowed or missing The following strategy has been adopted and must be followed in level 2 processing to remain compatible with level 3 programs
37. f CCD optical axis CAfov F32 1 Total field of view dec degs CAfovport F32 1 partial fov from port side to nadir CAfovpix 132 1 pixels visible in fov CApsfov F32 var pixel view angle table from port see general note 6 CApside 132 1 CCD port side flag CAsscan 132 1 Site start scan CAescan 132 1 Site end scan CAlooks 132 1 Number of looks in spectral image CAlooksp 132 1 Look spacing in spectral image CAlookc 132 1 Centre look pixel in spectral image CAsumdch 132 1 Number of channels per band summed in enhanced spectral CAsrcpres 132 1 SRC image present flag O no 1 yes CAsrcbands 132 1 SRC no of bands CAsrcchan 132 1 band used for src CAsrcpix 132 1 SRC no pixels CAilspres 132 1 ILS present flag O no 1 yes CAilsbands 132 1 ILS no of bands CAilspix 132 1 ILS no of pixels CAbstart 132 var band start of image data CAbend 132 var band end of image data CAwavc F32 var wavelength centre CAwavh F32 var wavelength half bandwidth CAcalfile C8 32 Calibration file name CAradsc F32 1 Radiance scaling multiplier CArunits C8 32 Radiance units CAiunits C8 32 ILS irradiance units CAimgmin F32 var Image bands minimum excluding zeros CAimgmax F32 var Image bands maximum excluding overflows Caimgzer 132 var Image bands zeros CAimgovr 132 var Image bands overflows Remote Sensing Scanner Processing System c Azimuth Systems 1996 2003 Version 3 00 37 20030131 Azimuth Systems User Guide AZGCORR CAsrcmin F
38. from sensor frame to vehicule frame etc In all cases for the highest accuracy GPS position needs correction against a fixed base station ie using techniques of Differential or Kinematic processing Inputs to azgcorr are run time parameters from the command line Level 1B HDF Level 2 HDF or a combined Level 1B HDF and related BIL BSEQ image file Outputs are a brief run listing and a Level 3 file Details the scanner optics are obtained from the command line or HDF file defaults Levels refer to the NASA definition of satellite or airborne image processed status The basic definition of these are Level 0 raw instrument acquired data no corrections Level 1A radimetric corrections applied Level 1B as 1A but with synchronised per scan geo location data included Level 2 products derived from Level 1data Level 3A Level 1 data geo corrected Level 3B as 3A but with ground control used for precise location Level 3A processing corrects the image data and interpolates an output image on a regular grid ina recognised map projection coordinate space aligned at a fixed spheroid height usually zero It may only approximately match a map in that projection as a map is in essense a 2D representation of the surface of the geoid plus the topography Level 3B processing uses digital elevation model DEM data as well as other calibration values groudn control points GCPs to achieve precise location that will be optimum for the navigation DEMs and co
39. ge data input to azgcorr must have been processed or imported to an internal HDF file using the correct programs in the Azimuth Systems package to ensure that all data items are present and as expected The one exception is Level 2 data the basis of which is image data extracted from a Level 1B file with azexhdf massaged by a user program and input to azgcorr still in BIL or BSEQ format along with its originating Level 1B HDF file Navigation data on the internal HDF files is always geodetic latitude longitude spheroid height pitch roll heading and typically in GPS WGS84 datum The conversion to a local datum and map projection with or without DEM correction is performed just prior to image correction this allows for maximum flexibility It is important to note that all appropriate data items DEM etc must be on the same datum and projection This is discussed below Level 1B processing has two main functions for the raw image data instrument calibration and corrections have to be applied and the data converted to units of radience this allows data from different instrumenst to be compared and used for combined calculations Navigation data for Level 1B has to be acquired from suitable instruments or processed to achieve ECEF coordinates GPS data both position and attitude as obtained from a GPS receiver is inherently ECEF INS and combined INS GPS needs post processing to allow for INS drift local gravity analmalies conversion
40. in this case the gap parameter may need to be increased to 6 8 or even 10 to avoid gaps at the image edge The nature of the sampling process in both line scan ATM and CCD CASI scanners results in the DN value obtained for a pixel being a measure of the reflection source by up to two pixels from the centre of a given pixel and controlled by the pixel response function sort of Gaussian When interpolating observed scan data to get a rectilinear output no interpolation method is any more accurate than another just different and all only an approximation to the value that would be obtained if the output pixel was measured directly With this in mind it is suggested that any scientific operation eg atmospheric correction is performed on the Level 1 data and geometric correction applied to this Level 2 product Any none Remote Sensing Scanner Processing System c Azimuth Systems 1996 2003 Version 3 00 7 20030131 Azimuth Systems User Guide AZGCORR scientific operation eg classification is performed on the interpolated geometric corrected image where pixels are in their correct geometric relation with each other 3 7 CASI and other CCD scanner corrections Data from this type of scanner may require some extra processing options to cater for the three possible data components recorded in the different operating modes of the instrument image data spectral data and ILS Briefly the data types consist of rec mode i
41. items 3 8 Viewing the results Interpolated image items can be converted to BIL or BSEQ files by the azexhdf utility and input into any standard image processing package Coordinates output as listing during the azgcorr run can be used to relate the images to maps Using the GeoTIFF output option in azexhdf produces a file containing image data and its registration coordinates this format is compatible with ERDAS and other image processing packages CASI none image items spectral enhanced spectral and ILS can be obtained on BIL or BSEQ format files and their related coordinates on separate files for use in user programs Remote Sensing Scanner Processing System c Azimuth Systems 1996 2003 Version 3 00 8 20030131 Azimuth Systems User Guide AZGCORR 4 Using azgcorr 4 1Introduction As supplied azgcorr is a unix command line program and is used as any other unix utility The program is controlled by a selection of command line parameters expects certain input files and generates program execution message output along with an output image data file An example of the simplest run azgcorr p 55 1 a1 hdf 3 a3 hdf This will use navigation and level 1 data on file a1 hdf and correct and output an image to file a3 hdf with a 5 metere square pixel size By default UK National grid coordinates will be used and all input bands will be processed The program has potentialy long run times so running from a shell script that include
42. l of file Prcdate C8 32 File creation date PRhostn C8 64 Host name of creating workstation PRhostid C8 16 Host ID of creating workstation PRsoftware C8 64 Processing software copyright notice VGroup MISSION Contains all pre flight operations and target delimiting values Site limits may be either or both of time and scan and are inserted by SITEINIT CASI details are inserted by CASCHK and are obtained from an analysis of the complete CASI data file or files Vgroup name MIS Vgroup title Mission Data item prefix MI Item name type maxv description Midesc C8 64 Vgroup description Mission and site details from flight logs Mlprog1 C8 40 Vgroup 1st processing program name Mlprog2 C8 40 Vgroup 2nd processing program name Micopyw C8 64 Data copyright notice Mlairc C8 32 Aircraft name Mipilot C8 32 Pilot name Remote Sensing Scanner Processing System c Azimuth Systems 1996 2003 Version 3 00 31 20030131 Azimuth Systems User Guide AZGCORR Minavig C8 32 Navigator name Mloper C8 32 Operator name Mlibase C8 32 Sortie base Midate C8 16 Flight date Mifltno C8 32 Flight number Mlprojco C8 64 Project code Mipiaff C8 64 Principal investigator and affiliation Mitarget C8 64 Target name Mifline C8 32 Requestors flight line name number Mlaspeed C8 32 Airspeed Mitrack C8 32 Track Mlalt C8 32 Altitude Mlweath C8 128 Weather Micloud C8 32 cloud cover Miland C8 32 land type and amount Micomm C8 128 Comments Mlfnum
43. libraries NSCA provide utilities for viewing data item contents and items The AZSPS utility program is supplied which allows for general listings ascii files of multiplexed vector information and application specific files containg image data BIL BSEQ GeoTIFF and TIFF are cater for See azexhdf user guide for more details The HDF files used in azgcorr contain all the navigation and scanner image data as well as all the related metadata items for a site The following strategy has been adopted for AZSPS file contents a all post processed navigation and scanner image data is contined in a level 1 file this will be a level 1a if no navigation is present or 1b with navigation a file will only contain data for one scanner and for one site b a Level 1b file processed by azgcorr may be used to generate a Level 3 file this will contain all the navigation and meta data items of the Levelib it will NOT have the level 1 image data present it will have the geocorrected image data it will have a mapping MP vgroup with mapping details used in the geocorrection Bz Se De De Remote Sensing Scanner Processing System c Azimuth Systems 1996 2003 Version 3 00 9 20030131 Azimuth Systems User Guide AZGCORR 4 3 External data files used by azgcorr azgcorr may be supplied with a few binary files containing correction grids for certain map projections and for spheroid to geod corrections The user only has to supply the approriate
44. ling and thus relate to the local gravity normal Positions were obtained by angular triangulation or optical or microwave trilateration Both sets of observations have varying errors which are minimised not removed by network adjustment A network of observed points both position and height can then be filled in on the ground with more levelling or other techniques or used to scale a series of stereographic aerial photographs from which height and position details can be measured using a stereogrammetric plotter In general height are an order of magnitude less accurate than positions On the other hand GPS surveying observes both position and height simultaneously in fact the observation is the 3D axis position of the observation site relative to the centre of the satellite orbit earth centre With appropriate equipment and techniques it is possible to make this 3D observation to a few millimetres More importantly each GPS site is essentially independent from other observations errors being related mainly to satellite constellation geometry This allows static site and vehicle positions to be independently observed but retain a very high degree of relative accuracy As can be expected there is a problem relating positions obtained from GPS observations and those from traditional geodetic surveying There is no simple transformation to solve this to any degree of accuracy beyond a few metres at best a fudge is possible like the recommended OS
45. mat grids see below NTF contour or grid files or a flat file NTF files must comply with the appropriate OS format description for layout and content azgcorr saves or creates a grid from these files to cover the image area requiring correction Previously gridded data may not be altered in grid spacing NTF contour files are converted internally using a user requested grid interval to form the required grid The requested grid interval must be chosen to be equal to or greater than the output pixel spacing If too small an interval is used the program run time will increase considerably the program may run out of memory and no improvement in image correction will be achieved two times the pixel spacing is more than adequate DEMs created from LIDAR observations should be processed to regular grids where the x y coordiantes are the centres of each grid node As discussed previously the x y coordinates have to transformed through the same method as the scanner image data So if UK99 is used for scanner navigation conversion it must be used in post processing the LIDAR navigation It should also be noted that problems may occur due to misalignement of the LIDAR and scanner grids due to different methods used in calibrating the view vectors of each instrument In the case where the DEM does not completely cover the image grid the missing parts are filled with default or user supplied fill values before the geoid spheroid correction is made if
46. navigation on the earth s surface is referenced to a set of axes and a model which describes the static and dynamic geometry of the earth and navigation platform this is a geodetic datum For the sake of this discussion we can ignore all parameters except earth geometry and time For brevity a datum is given a name or even a mnemonic throughout the world there are several hundred different datums Current GPS datum is called WGS84 World Geodetic System agreed in 1984 To make position observation and calculations tractable the shape of the earth is represented by the nearest simple geometric figure consistent with the desired accuracy For survey use sufficient accuracy is obtained with a the earth represented by an ellipse rotated about the earth s north south spin axis This 3D figure is called a spheroid or ellipsoid by some texts Of course this simplified figure only approximates the actual earth surface the geoid at any point To relate the two figures a local origin is chosen with measured lateral position and assigned vertical position height All heights for a locality are then relative to this reference point In UK the point is at Newlyn Cornwall and the height zero is related to mean sea level A locality height topographic map in grid form is also known as a digital elevation model It is important to note that before the days of GPS heights and positions on maps were obtained separately Heights were by bubble or optical level
47. neral note 4 SCvplane 132 1 Image view y plane position metres SCposimag F64 var Image position coordinates for SCposn 1 see general note 5 SRCposimag F64 var SRC image position if different from Spectral or Enhance Spectral data image SCposscan 132 1 Position info per scan content flag SCsused 132 var scans used in level 3 image field scan numbers SCbused 132 var bands used in level 3 image level 1 band numbers SCpxyn 132 1 No of pixels per side of tile SCpxy_sc F64 1 Image xy scale multiplier CAimgxy 132 var Image xy coordinates CAsrcxy sl32 var SRC xy coordinates CAilsxy sl32 var ILS xy coordinates CAimage SDS 3xvar Image data spectral or spatial bands CAsrc SDS 3xvar SRC data scene recovery for spectral mode CAils SDS 3xvar ILS data CASI notes 1 Descriptions starting with indicate values transferred without alteration from the CASI data file Full details can be found in CASI documentation General Notes 1 Data types C8 CHAR8 8 bit characters used for text strings which are zero terminated 132 INT32 32 bit signed integers 132 INT32 32 bit integers containing scaled floating point values UI32 UINT32 32 bit unsigned integer F32 FLOAT32 32 bit floating point F64 FLOAT64 64 bit floating point SDS see below format indicated by SCHDFfmt may be UINT16 or FLOAT32 Item dimensions marked as variable var or SDS may be of any length Variable and SDS items only appear in VGroups if they have 1 or more valu
48. ntrol 3 Keywords Daedalus ATM geocorrection geometric correction geolocation geocoding airborne remote sensing parametric geocoding Remote Sensing Scanner Processing System c Azimuth Systems 1996 2003 Version 3 00 4 20030131 Azimuth Systems User Guide AZGCORR 3 Geo Correction Concepts 3 1 Goals for correction Stated simply the purpose of the program is to produce an output image which overlays an existing map The rotating mirror ATM or pushbroom CASI Hymap or other scanners have positions calculated for every pixel and then the image is interpolated to a rectilinear grid which may be projected to a plane relative to the aircraft or related to existing topographic data In azgcorr it is important to note that this ground referencing is only achieved by using observed scanner aircraft position and attitude and referencing scan positioning to elevation DEMs information Ground control points are ONLY used for calibrating DEMs and geoid spheroid separation data In all the following discussion it should be noted that the navigation attitude used HAS to be that attitude experienced by the scan head If a gps attitude unit is used or a INS AHRS IMU that is NOT mounted on the scan head AND the scan head has shock mounts or a stabilised platform then the measured attitude WILL NOT be that of the scan head and azgcorr WILL NOT produce optimum results 3 2 Navigation relation to Datums and Spheroids All
49. o the conversion 5 4 changing the datum shift and map projection This will be required in the cases where the desired map projection does not include an integral shift the majority or an accurate local shift is being used azgcorr d7 0 113 7 57 1 98 4 0 05 0 18 1 7 1 28 mUTM 7 then as for ex2 ex4 Here the Transverse Mercator projection has been selected with a user central meridian of 7 degs west A fictitious 7 point datum shift has been supplied and the default spheroid of International ED50 has been used for both the datum shift and projection Origin of the projection is at the equator and grid coordinates go from 0 at the equator northwards and form 50000 at 7 degs west Commonly used datum shift and spheroid values are described in Appendix A Remote Sensing Scanner Processing System c Azimuth Systems 1996 2003 Version 3 00 11 20030131 Azimuth Systems User Guide AZGCORR 5 5 improving mapping accuracy without a DEM Positioning based on WGS84 provides the latitude and logitude of the scanner as well as its height above the WGS84 spheroid With the default settings azgcorr projects the corrected image to zero above the spheroid for most sites this will be in error so for coastal or relatively flat land sites where no DEM is available an improvement in mapping accuracy can be obtained by applying a spheroid to geoid correction form the internal tables or an external file azgcorr hsu then as ex2 ex5 azgcorr
50. on info per scan content flag SCsused 132 var scans used in level 3 image field scan numbers SCbused 132 var bands used in level 3 image level 1 band numbers SCpxyn 132 1 No of pixels per side of tile SCpxy_sc F64 1 Image xy scale multiplier ATimgxy 132 var Image tiles coordinate list ATdata SDS 3xvar Image data ATM notes Remote Sensing Scanner Processing System c Azimuth Systems 1996 2003 Version 3 00 36 20030131 Azimuth Systems User Guide AZGCORR 1 Items sbend rgyro hddt and cct are specific to the original ATM system 2 ATfov and ATfovp if ATfov 0 0 then a reduced filed of view has been applied to the original ATpixred is the reduced number of pixels ATfovp 0 this same number ATfovp 1 port field of view angle from nadir and ATfovp 2 starboard field of view angle 3 From Jan 2003 ATM level 1 files may contain less than the total number of bands recorded The basic ATM recorded by the AZ16 data system acquires 11 bands 1 11 if all bands are saved then ATbands will contain 11 values from 1 11 or optionally ATbands will not be present and SCbands will 11 If it contains less then SCbands will be lt 11 and ATbands will have the list of saved bands these will be numbered as for the original acquired bands AND will be in the user requested order NOT increasing band number order There may be as few as 1 band for a thermal only flight Bands not saved will not take space on the HDF file Note the VGroup i
51. parameter that gives the file path to these Other files which may be needed are user supplied digital elevation models DEMs These may be from topographic mapping LIDAR or other sources Details of their use is in the section on how to use DEMs as well as the DEMs in Option and Parameters below 4 4 System requirements and Practical aspects of running the program Versions of azgcorr and any support utilities can be supplied for use on Sun workstations under Solaris version 2 3 or higher and PCs running any version of Linux In either case the minimum system configuration should be 32 Mbyte of RAM hardware floating point 2x the maximum image file size of free disc space a roll partition of at least twice the size of the RAM Processing speed is directly related to CPU floating point performance ie therefore CPU clock rate and disc access rates With the amount of data and calculation required correction of all bands for even a moderate sized site can take some time so the following details will help to avoid wasted time azgcorr run times will be extended by a increased number of bands b increased number of scan lines c reduced pixel size d presence of DEM e presence of other programs running on the CPU f amount of useable memory g shortage of disc space for output file azgcorr may run out of memory with an inappropriate combination of a too small pixel size and b diagonal flight line and c too m
52. pplied without any claim as to their accuracy it is the user s responsibility to verify accuracy and relevance to their use Spheroid values Spheroidname AZSPS A 1 f Notes code International 0 6378388 00 297 00 Hayford 1910 Airy 1830 1 6377563 3963534 299 32496459380 UK National Grid WGS 1972 2 6378135 00 298 26 WGS 1984 3 6378137 00 298 257223563 Everest 1830 4 6377276 345 300 8017 Everest revised 5 6377298 556 300 8017 Malayan 1830 6 6377304 068 300 8017 Bessel 1841 7 6377397 155 299 1528128 Clarke 1858 8 6378293 645 294 2600 Clarke 1866 9 6378206 400 294 9786985 Clarke 1880 10 6378249 200 293 4660213 IGN Clarke 1880 11 6378249 145 293 465 MOD Helmert 1907 12 6378200 000 298 3 War Office 13 6378295 000 296 0 Krassovsky 1940 14 6378245 000 298 3 Hough 1956 15 6378260 000 297 0 Fischer 1960 16 6378155 000 298 3 Mercury Fischer 1968 17 6378150 000 298 3 Mercury revised NWL 8D 18 6378145 000 298 25 Australian National 18 6378160 000 298 25 South American 1969 19 6378160 000 298 25 Ghana National 20 6378295 000 296 00 OS GB GRS80 21 6378137 000 298 25722154381 GRS80 22 6378137 000 298 25722210100 Datum shifts These are all FROM WGS84 TO the named spheroid d s are in metres r s in seconds sc in ppm spheroid dx dy dz rx ry rz sc Airy 1830 446 446 125 157 542 060 0 1502 0 2470 0 8421 20 48
53. procedure for GPS to National Grid For purely economic reasons the correct solution for a whole country will never be performed ie reobserve all original ground points by GPS and recompile all maps Remote Sensing Scanner Processing System c Azimuth Systems 1996 2003 Version 3 00 5 20030131 Azimuth Systems User Guide AZGCORR The relationship between a simple spheroid and its geoid is obtained by a combination of satellite orbit observation satellite height above sea level measurement and details of the earths local observed gravity Merging and adjusting this lot using spherical harmonics produces a geoid spheroid separation map for the spheroid in question The appropriate sum of the spheroid height geoid spheroid separation value and the geoid DEM height allows the height of for example an aircraft above a DEM to be obtained only using GPS observations to 5 metres or so The highest accuracy can only be achieved by GPS ground control points used to calibrate stereo photographs from which new DEMs are obtained Or by means of the latest laser topographic scanners positioned by GPS LIDAR To summarise for our use of GPS for remote sensing aircraft surveying a surveying and platform positioning is by GPS which gives an observation a 3D position b relating dynamic and static observations using GPS is easy to a few tens of centimetres c relating these observations to existing maps requires various adjustments the firs
54. r file during a BIL file output must be used with B file will be fp bil stats option Bh c requests output histogram to header stats file for all data c number of columns in histogram c 0 gives 256 Remote Sensing Scanner Processing System c Azimuth Systems 1996 2003 Version 3 00 21 20030131 Azimuth Systems User Guide AZGCORR option Cx fp create binary file with CASI spectral and ILS fp file path for created file file contents for each image pixel 0 pixels and each image line 0 lines coordinates are pairs of xy s grid coords format is tenths of metres in signed long NB must be run separately from BIL p may be used option Cr fp as for Cx but coords are col row pairs to match the row column pairs match the SRC image format is uint16 NB must be run separately from BIL p may be used option T fp convert any level image data to TIFF file tif option G fp convert level 3 image data to GeoTIFF file tif fp file path for created file 1 these files are TIFF level 6 0 or GeoTIFF 1 1 4 pixels are band interleaved by pixel BIP and there are the requested no of bands samples per pixel in 16 bit unsigned 2 Note that some readers may not allow more than 3 bands 3 Only TM UTM UKNG projections are supported in this version option d dn image data item name if not default default is to use the standard item for ATM and CASI option S fp convert image data and output to Sun raster file fp file path for c
55. r imply that a level 1 file will be in flight direction down the file with pixel zero on the right By deafult a level 3 north up file will be going north down the file with pixel zero to the west directions can be changed in level 3 processing Option I can ve used to reverese the line order convention for output to a file Remote Sensing Scanner Processing System c Azimuth Systems 1996 2003 Version 3 00 25 20030131 Azimuth Systems User Guide AZGCORR 7 4 4 Sun raster output A SunRaster format file can be created from 1 or 3 selected bands to give an image viewable using utilities such as imagetool or XV Note that if the selected image is beyond a certain size or contains too may colour levels these utilities will resample and remap the pixels Option S selects the output format and provides the output file c or m provides the band from the HDF file and selects RGB colour or monochrome output file format p can be used to restrict the image patch eg azexhdf t1 hdf S a sunr c 532 Will obtain a SunRaster RGB file for bands 5 for red 3 for green and 2 for blue of the whole default image item on t1 hdf 7 4 5 TIFF output A TIFF file containing 1 3 or more bands can be created using the option T fp Data limiting options as for BIL apply to select bands pixels and lines Pixel format is limited to UINT16 The created file can be used in many image display packages but not all can handle more than 3 bands 7 4
56. r scan lines with the geolocation navigation NVscsecs is the gps time of the scan number in the same index entry of NVscnum Geographic location of a scan is then calculated by interpolation using gps time VGroup SCAN COORDINATES Contains post processed and interpolated navigation on a per scan basis This is the Level 1B geolocation data on a one location point per scan basis Common indexed entries in the CO vectors give the location data for the same index entry for the lline dimension in the image data SDS VGroup name SCO Vgroup title Scan coordinates Data item prefix CO Item name type maxv description COdesc C8 64 Vgroup description Navigation data interpolated to scan times COprog1 C8 40 Vgroup 1st processing program COprog2 C8 40 Vgroup 2nd processing program COoffs 132 1 Offset code for scanner in aircraft COstime 132 1 Time of site start dec secs COetime 132 1 Time of site end dec secs COsscan 132 1 Scan number of site start COescan 132 1 Scan number of site end COscans 132 1 Total scans with navigation COscint 132 1 Interval of scan number for scans with navigation COtime 132 var Time GPS dec secs COutc 132 var Time UTC dec secs COlat 132 var Latitude dec degs COlng sl32 var Longitude dec degs COhgt sl32 var Spheroid height metres COalt sl32 var Altitude above local datum metres COroll sl32 var Roll dec degs COpitch sl32 var Pitch dec degs COhead sl32 var Heading dec degs COq
57. reated file option c rgb band nos for colour image Sun raster file option m c band no for monchrome image Sun raster file option p pO pn l0 in image patch limits pixels and lines pO pn pixel limits in the range 0 to number pixels in the image 10 In scan line limits in the range 0 to lines in image This can be used for Sunraster BIL and image item listings option ph does image listing in hex Switches image listing between integer and hex option pbseq if present does image list in BSEQ order If not present default image list in BIL order option po only image listing done Suppresses listing of other HDF data items option r output DN values as radiance using default scaler Default is to save image items unchanged from the HDF file Remote Sensing Scanner Processing System c Azimuth Systems 1996 2003 Version 3 00 22 20030131 Azimuth Systems User Guide AZGCORR option rmm user supplied multiplier for DN scaling for BIL output m user Supplied multiplier option bl bO b1 1 select bands to be converted to output b0 list of band numbers 1 bands and in the order for saving option br b0 bn select bands by range bo bn bands will be saved from bO to bn option l line order reversed on output to files Scan lines are ouput by default as HDF levels 1 and 2 scan 0 first HDF level 3 northern most scan first If I is present this order will be reversed option v vector saving listing options
58. s creating an output file compatible with an image processing package used for anyalysis makes for a convienient background or overnight batch run It is of course understood that there are some advantages in being able to run the program perhaps on restricted data sets in a semi interactive mode even to the extent of instant screen display Work is underway to provide a complete interactive version during 2003 4 2 Internal data files used by azgcorr It was decided from the start of the Azimuth Systems Scanner processing System AZSPS of which azgcorr is one of a dozen programs to use the NSCA HDF scientific file format This offered certain advantages of compatibility and access to basic file handling and data utilities AZSPS currently uses HDF4 of release 4 114 Full details can be obtained from the main HDF web site http ndf ncsa uiuc edu The HDF format has considerable flexibility but only a basic subset has been used to create a file with a two level hierachy Data items Vdatas which may have single values or vectors are grouped together to form Vgroups On the AZSPS implementation Vdatas have been used for all items which are limited to 1 dimension except main image data which is stored as a 3 dimensional SDS scientific Data Set item Every data item is identified by a name and this is used elsewhere in this document to refer to items These AZSPS HDF files can be accessed in user software using the appropriate HDF
59. svec F64 7 Datum shift vector for single point transformations MPimx0 F64 1 Image origin grid x MPimy0 F64 1 Image origin grid y MPtiles 132 1 number of tiles in image MPracs 132 1 MPcxy F64 var tile coordinates VGroup LEVEL 2 Contains details of user application level 2 processing Vgroup name LV2 Vgroup title Level2 Data itemprefix L2 Item name type maxv description L2desc C8 64 Vgroup description Level 2 user processed data L2prog1 C8 40 Vgroup 1st processing program L2prog2 C8 40 Vgroup 2nd processing program L2para1 C8 128 User program parameter list1 L2para2 C8 128 User program parameter list2 VGroup ATM Contains ATM scanner recording parameters and recorded calibrated or geometrically corrected image data stored as 16 bit integer to level 1b and either 16 bit integer or 32 bit floating for level 2 and level 3 Level 1 data is inserted by ATM_1 Data recorded with the DEI320 has 12 channels and from the AZ16 11 channels Note this is for pre 2001 data all ATM data from 2001 uses ATM2 below Vgroup name ATM Vgroup title ATM Data item prefix AT Item name type maxv description ATdesc C8 64 Vgroup description ATM scanner details calibration and data ATprog1 C8 40 Vgroup 1st processing program ATprog2 C8 40 Vgroup 2nd processing program ATprog3 C8 40 Vgroup 3rd processing program ATprog4 C8 40 Vgroup 4th processing program ATsbend 132 1 Sbend correction applied in scanner flag O no 1 yes Note
60. t file contains rm a3 hdf azgcorr mUK99 uk99grid eh DEMforsite p 2 2 bl 5 3 2 1 1 a1 hdf 3 a3 hdf azexhdf a3 hdf azexhdf bl 1 2 3 1 h a3 hdf G a3 tif a The old level 3 files are first removed b azgcorr run does correction on UK National grid 1999 version and uses a local DEM Pixel size is 2 metres and a three band RGB set is produced Interpolation is left to cubic default c first azexhdf just generates a content listing of the level 3 HDF file d second azexhdf creates a GeoTIFF file of the level 3 3 band image note this has 16 bits per band this will be compatible with ERDAS 8 5 ERMAPPER etc Remote Sensing Scanner Processing System c Azimuth Systems 1996 2003 Version 3 00 13 20030131 Azimuth Systems User Guide AZGCORR 6 Program execution Options and Parameters The description below expands on the concise version obtained in the standard unix usage method obtained by typing azgcorr help It should be noted that the most up to date information is from the usage version Notes on the description below a Letters preceeded by minus signs are the parameter names as summarised in the Usage listing b Filenames always implies full unix paths c Command line parameters and values may be in any order d Latitude and longitude values in signed decimal degress are ve for south and west e All units of distance are in metres f Option requirement in typical runs are optional unless stated option
61. t of which is the transformation of the aircraft position on the GPS datum to the local mapping datum moderate accuracy few metres is done using an observed data fudge d more accuracy requires field GPS observation of control points The default method used in azgcorr to transform from GPS satellite datum WGS84 to UK National Grid uses the Ordinance Survey recommended National Grid ETRF89 Transformation Parameters 2 1995 ver 1 2 claimed to be accurate to the 2 metre level A second method available from azgcorr version 4 4 0 Jan 2003 uses the release of the OS correction grids and interpolation methods OSTN97 and OSGM91 provided as option UK99 described in the OS User Guide v1 2 1999 For use in azgcorr this involves a large 5Mbyte external correction file so it is not set as the default UK95 covering UK only will remain the default if no other method is selected An additional correction grid using OS details in OSTNO2 and OSGM02 will be available shortly 3 3 Map projections The default procedure for UK outlined above does a one step conversion from WGS lat long height to UK national Grid map projection coordinates The more usual method of transformation does this in two steps allowing more flexibility First the GPS position latitude longitude and spheroid height on satellite datum WGS84 is transformed to a local datum lat long height Then the geographic spheroidal coordinates are transformed to a suitable rectiline
62. t we tend to use hdf as the HDF file extensions a for ATM data and c for CASI ccd scanner data To avoid confusion the level 1 data considered in examples below is assumed to have navigation all on WGS84 The program may only used for the period and on the system or systems it is licensed for if any of these criteria are not met an error message will appear and the program will terminate 5 1 to obtain online program help azgcorr with no parameters will show the program version and basic run requirements azgcorr help will give an uptodate concise description of all parameters 5 2 basic correction azgcorr p 55 1 a1 hdf 3 a3 hdf ex1 Image level 1 input is from a1 hdf desired pixel size is 5 metres square and image output will be on a3 hdf Important defaults whcih would be applied are map projection would be UK National Grid 1995 version and all input bands would be corrected image would use bicubic interpolation To limit the number of bands azgcorr p 5 5 bl 53 2 1 1 a1 hdf 3 a3 hdf ex2 would give 3 ATM bands suitable for a pseudo RGB image these would be in R G B order on the a3 hdf file 5 3 changing the map projection no datum shift required azgcorr mUK99 osgb99 rest as ex2 ex3 Now the 1999 version of the UK National grid will be used projection correction values will be from file uk99grid Other projections not requiring specific datum shifts are Dutch and New Zealand the shift from WGS84 is built in t
63. tem content SPATIAL image several bands of continuous pixels ILS same number of bands of single pixels SPECTRAL image many bands of spaced out pixels SRC single band continuous pixel image for scene positioning ILS same number of bands as image for single pixel ENHANCED image many bands of continuous pixels but of restricted image width SPECTRAL SRC single band continuous pixel image for scene positioning ILS same number of bands as image for single pixel Using the appropriate options AZGCORR processes these items as follows spatial image spectral SRC enhanced spectral SRC and enhanced spectral image handled as ATM ie continuous image all three methods of interpolation may be used and a rectilinear interpolated image results spectral image enhanced spectral image and ILS geometrically corrected grid coordinates are calculated for each pixel and saved on the HDF file to allow positioning over the SRC image Note that the data items will also be copied to the level 3 file Coordinates are saved in vectors CAimgxy for image pixels and CAilsxy for the ILS pixel Note that ONLY selected lines and bands are tranferred to the level 3 file spectral image a special option cspi allows spectral data to be processed as though it was a continuous touching pixels space between pixels is filled by the selected interpolation method Note that interpolation option has no affect on the pixel coordinates calculated for none image
64. tems ATwavu ATwavl ATgains ATradsc ATimgmin ATimgmax ATimgzer ATimgovr will have the same dimension as ATbands and the contents will refer to the same bands as the numbers in ATbands VGroup CASI Contains CASI scanner recording parameters and recorded calibrated or geometrically corrected image data stored as 16 bit integer to level 1b and either 16 bit integer or 32 bit floating for level 2 and level 3 Up to three sets of image data may occur Image SRC and ILS see ITRES CASI documentation Contains Vgroup name CAS Vgroup title CASI Data item prefix CA Item name type maxv description CAdesc C8 64 Vgroup description CASI scanner details and data CAprog1 C8 40 Vgroup 1st processing program CAprog2 C8 40 Vgroup 2nd processing program CAprog3 C8 40 Vgroup 3rd porcessing program CAprog4 C8 40 Vgroup 4th processing program CAserial 132 1 CASI scanner serial number CAswver C8 32 CASI scanner software version number CAexa C8 64 Exabyte tape external label name CAfnum 132 1 Field tape file number CAconfig C8 32 Scanner configuration file name CAsday 132 1 Target start day of year CAstime 132 1 Target start time HHMMSS CAmode 132 1 CASI operating mode flag 0 spatial 1 spectral 2 full frame CAg F64 4 G coefficients CAinteg F32 1 CCD integration period msecs CAapert F32 1 CASI file header reported aperture CAfapert F32 1 Aperture appearing in majority of none dark frame headers CAoaxis F32 1 Pixel o
65. th and gaps A typical use of this is to get navigation items or scan sync items vf gives an output file vm selects multiplexed mode and repeated use of vn gives the required items Note this is for none SDS items only eg azexhdf vf nav dat vm vn NVtime vn NVlat vn NVIng vn NVhgt t1 hdf Wiill obtain a 4 column file with all entries of GPS time latitude longitude and height 7 4 3 HDF file reformatted to BIL or BSEQ Image items are extracted and reformatted to BIL or BSEQ files with the options BIL or BSEQ to select the file format along with an appropriate file path to contain the output The following optional parameters can be used to modify the output d to select a none default item ATM is ATdata CAS is CAimage bl to select one or more bands p to limit pixels and lines Bs to get a summary statistics file and Bh to get a histogram for each selected band Bv will obtain extra coordinate details for level 3 files BIL and BSEQ output files data entries are in the same format as level 1 files ie binary unsigned integers Pixels are output with file indexed zero first and lines with line indexed zero first Bands are output in the order requested by parameter bl eg bl 5 3 2 1 would give these three bands in order 1 2 3 on the output file if the file was BIL the sequence would be line 0 band 5 pixels 0 to n line 0 band 3 pixels 0 to n line 0 band 2 pixels 0 ton line 1 band 5 ssassn etc Line and pixel orde
66. time2 sl32 var Time of position set 2 observations GPS dec secs NVlat2 sl32 var Latitude dec degs NVIng2 132 var Longitude dec degs NVhgt2 132 var Spheroid height metres NValt2 sl32 var Recorded altitude above local datum metres NVqual2 UI32 var position set 2 quality flags NVasecs2 sl32 var Time of attitude set 1 observations dec secs NVroll2 132 var Aircraft roll dec degs NVpitch2 sl32 var Aircraft pitch dec degs NVhead2 sl32 var Aircraft heading dec degs NVaqual2 UI32 var attitude set 2 quality flags NVsctcor F64 1 Time correction from nav observation to scan observation NVscnum sl32 var Scan number see below NVscsecs 132 var Scan synchronisation time GPS dec secs see below NVtime_sc F64 1 Scale multiplier for time NVasecs_sc F64 1 Scale multiplier for attitude time NVlat_sc F64 1 Scale multiplier for latitude NVIng_sc F64 1 Scale multiplier for longitude NVhgt_sc F64 1 Scale multiplier for height NVroll_sc F64 1 Scale multiplier for roll NVpitch_sc F64 1 Scale multiplier for pitch NVhead_sc F64 1 Scale multiplier for head NVscnum_sc F64 1 Scale multiplier for scan number NVscsecs_sc F64 1 Scale multiplier for scan sync time Notes 1 Navigation vectors are stored as scaled integers format s132 file values are to be multiplied by the appropriate scale to obtain a double precision floating value 2 Spheroid and datum codes are documented in Appendix A 3 items NVscnum and NVscsecs link scanne
67. ual UI32 var Interpolation quality OR d flag 0 interp extrap 1 posn 2 attitude COtime_sc F64 1 Scale multiplier for time COlat_sc F64 1 Scale multiplier for latitude COlng_sc F64 1 Scale multiplier for longitude COhgt_sc F64 1 Scale multiplier for height COroll_sc F64 1 Scale multiplier for roll COpitch_sc F64 1 Scale multiplier for pitch Remote Sensing Scanner Processing System c Azimuth Systems 1996 2003 Version 3 00 33 20030131 Azimuth Systems User Guide AZGCORR COhead_sc F64 1 Scale multiplier for heading VGroup MAPPING DETAILS This Vgroup is present on Level 3 files only and contains mapping parameters used for final image correction in AZGCORR Vgroup name MAP Vgroup title Mapping details Data item prefix MP Item name type maxv description MPdesc C8 64 Vgroup description Mapping parameters for level 3 MPprog1 C8 40 Vgroup 1st processing program MPsphc 132 1 Spheroid code for map projection MPdatm 132 1 Datum shift code from navigation to mapping datum MPproj 132 1 Map projection code MPIngO F64 1 Longitude of origin MPlat1 F64 1 Latitude of origin or 1st parallel MPlat2 F64 1 2nd parallel MPglat F64 1 Latitude of grid origin MPglng F64 1 Longitude of grid origin MPgx0 F64 1 Grid coordinate at grid origin MPgy0 F64 1 Grid coordinate at grid origin MPscf F64 1 Project scale factor at projection origin MPdshc 132 1 Datum shift code aquisition to mapping datums MPdsVG C8 16 Datum shift name MPd
68. ustrative purposes To be able to say that any pixels in a processed image has an error in positioning from it s defined image location of x cm where x is small is a totally different problem This requires both the optimum choice of appropriate navigation equipment and a series a predifined navigation and image correction steps prior to the generation of a final corrected image accurately overlaying the desired map If any of these steps are less than optimum x cm will get bigger and irregular with more error the image may only fit the map erratically So the bottom line to achieve user contentment is ultimate accuracy ECEF navigation followed by painstaking post processing perhaps scientific massaging to obtain derived data and then careful geocorrection azgcorr therefore performs the final step in the production of map fitting remote sensing images As described below it contains many options for selecting mapping details and image definition and interpolation This allows it to cater for many types of scanner data and output images on all the main survey grade map projections azgcorr and support utilities are currently available for Solaris and x86 Linux Supported scanners are ATM CASI processing of Specim and Hymap have also been performed 1 1 Future developments Further developments under way and available during 2003 a finalise Linux version b generalise scanner support to allow complete user definition c change int
69. y be either 4 Derived image views Images resulting from level 3 processing are projected to a surface different from the aquisition surface the selected surface is indicated by the SCviewty flag with values 0 as source image is as original and not resampled 1 mean sea level of local datum 2 to a plane parallel with the mapping spheroid fixed GPS flight height 3 to observed flight height corrrection 4 digital elevation model DEM in local datum 5 DEM Geoid Spheroid correction navigation to mapping spheroids 5 Image Coordinates The position of a resampled and corrected image is defined by a set of corrdinate values and increments With origin at pix 0 line O and using map projection grid coordinates SCposimag and SRCposimag values are 0 pixels 1 lines 2 x origin BL pixel 3 y origin BL pixel 4 xinc per pixel 5 yinc per pixel 6 xinc per line 7 yinc per line Using this vector the coordinates any any pixel pix line zero relative is given by x posimag 2 pix posimag 4 line posimag 6 y posimag 3 pix posimag 5 line posimag 7 Remote Sensing Scanner Processing System c Azimuth Systems 1996 2003 Version 3 00 39 20030131

azgcorr User Manual

Contents

Download Pdf Manuals

Related Search

Related Contents